Private Custom Tattoo Studio vs Walk in Shop

What is difference between working in your private custom tattoo studio against working in regular walk in or street shop.

Question itself was so unspecific that it turned out in to great discussion on how define which shop is exactly what and what point of tattoo artist career it would make sense to work one way or another.

This time our talked had guest from Latvia who is tattoo artist and co owner of tattoo shop Rigas Tinte who have some good points based on his experience.